Strange as it may sound, coming from me, I'm actually okay with this. It seems to me that at least part of the purpose of that group is to be a sort of support group for people who have experienced racism. Like any other sort of support group, it involves sharing very personal and painful experiences with others who've also experienced it and can therefore truly understand what they're going through. It really not that hard to see why it would make those involved uncomfortable to have non-members sit in on their meetings. Especially, if said people are there because they intend to publish an article about it.